a All public road and street mileage in the =
50 states=20
and the District of Columbia. For years prior to 1980, some miles of =
nonpublic=20
roadways are included. No consistent data on private road mileage are =
available.=20
Beginning in 1998, approximately 43,000 miles of Bureau of Land =
Management Roads=20
are excluded. 2010 Missouri and Wyoming's data are 2009.

d Transit system length is measured in =
directional route-miles. Directional route-miles are the distance in =
each=20
direction over which public transportation vehicles travel while in =
revenue=20
service. Directional route-miles are computed with regard to direction =
of=20
service, but without regard to the number of traffic lanes or rail =
tracks=20
existing in the right-of-way. Beginning in 2002, directional =
route-mileage data=20
for the Commuter and Light rail modes include purchased=20
transportation. 2005 and later years directional route-mileage data for =
the=20
Heavy rail mode include purchased transportation.

e These are estimated sums of all domestic =
waterways=20
which include rivers, bays, channels, and the inner route of the =
Southeast=20
Alaskan Islands, but does not include the Great Lakes or deep ocean =
traffic. The=20
Waterborne Commerce Statistics Center monitored 12,612 miles as =
commercially=20
significant inland shallow-draft waterways in 2001. Beginning in 2007, =
waterways=20
connecting lakes and the St. Lawrence seaway inside the U.S. are =
included.

f The large drop in mileage between 2000 and =
2001 is=20
due to a change in the source of the data. CO2 or other is =
excluded=20
for 2004 to 2008.

g Includes trunk and gathering lines for =
crude-oil=20
pipeline.

h Excludes service pipelines. Data not =
adjusted to=20
common diameter equivalent. Mileage as of the end of each year. Data =
includes=20
gathering, transmission, and distribution mains. Prior to 1985 data also =
include=20
field lines. See table 1-10 for a more detailed breakout of Oil and =
Gas=20
pipeline mileage. Length data reported in Gas Facts prior to =
1985 was=20
taken from the American Gas Association's member survey, the Uniform =
Statistical=20
Report, supplemented with estimates for companies that did not =
participate.=20
Gas Facts length data is now based on information reported to the =
U.S.=20
Department of Transportation on Form 7100. Since data for 1985 and later =
years=20
are obtained from the Pipeline and Hazardous Material Safety =
Administration,=20
data for these years are not comparable with prior years or with numbers =
published in the previous NTS reports.

NOTE

Eno Transportation Foundation has discontinued its oil =
pipeline=20
data for years prior to 2001.